The overall goal of the proposed R&D program is to develop and demonstrate a new approach for objectively measuring the functional impact of pain, and changes thereto, during the course of a patient's treatment. The approach is intended to be a supplement to existing methods for assessing patient functioning, which are presently based on self-report, clinician observation, patient and family concordance, and "snapshot" functional assessments by physical therapists and/or occupational therapists. The central objective of the Phase I effort will be to demonstrate the psychometric utility (i.e., validity and reliability) of the proposed new approach for assessing the functional impact of pain (FIP) in pain clinic patients with chronic or subacute pain. Success for construct validity in Phase I will be designed by demonstrating the accuracy of the new approach in predicting each of the conventional psychometric instrument scores via Bland- Altman analysis (and corresponding statistical tests for zero bias, equal standard deviations, and significant R2 values) based on an n-fold cross-validation technique. Additionally, inter-instrument correlations will be computed and exploratory factor analysis will be performed to assess the number of behavioral dimensions represented in the data. To demonstrate internal-consistency reliability, Cronbach's alpha and item-total correlations will be computed for each of the conventional psychometric instruments as well as for the new approach. Success for internal-consistency reliability will be defined by demonstrating values for Cronbach's alpha = 0.70 and item-total correlations in the range 0.30-0.70, which are the generally recommended values. Additionally, the "usability" (as contrasted with "functionality") of the new FIP assessment method will be assessed. Volunteers will be asked to complete usability surveys, the information from which will be used to improve the new FIP assessment method prior to implementation of the Phase II system. Functional ability is a crucial component of the assessment of any chronic pain condition. Although considerable attention has been given to the development of psychometric instruments that facilitate the assessment of pain-related disability, collection of accurate data via questionnaires remains an issue in practice (e.g., self- report measures, by their nature, do not reflect how the patient feels and functions in day-to-day activity). The proposed technology offers a novel method for overcoming present limitations in accurately assessing the functional impact of pain. [unreadable] [unreadable] [unreadable]